Elasticity measuring device for biological tissue

ABSTRACT

We disclose an elasticity-measuring device which can be inserted into a canal part of living body and which is capable of quantitatively measuring the elasticity of the biological tissue of inner side of canal part. The device consists of a probe base ( 5 ) and probes ( 7 ). The probes ( 7 ) are secured to probe base ( 5 ) and driven to press onto and return from biological tissue. According to the stress or hardness of the biological tissue measured by sensors on probes ( 7 ) and to the deviation between the probes ( 7 ) and the probe base ( 5 ), we can decide the elasticity of the biological tissue of inner side of canal part quantitatively.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a device for measuring the elasticityof the biological tissue.

2. Description of the Related Art

In the case of women, after the delivery of a child or in accordancewith the aging, since the muscle suspending the urethra goes slacked andhence its elasticity deteriorates, there is a tendency that incontinenceoccurs even for slight shock or impact. To cope with this physicalproblem, an operation for restoring the elasticity of the musclesuspending the urethra is performed in such way that suspension holesare provided in, for example, pelvis and the muscles around the urethraare suspended with the usage of the suspension holes. To perform anappropriate operation, it is necessary to evaluate an elasticity of themuscles that surround the urethra.

Since the urethra is located near the vagina, the evaluation ofelasticity of the muscles surrounding the urethra can be conducted bymeasuring the elasticity of the biological tissue of an inner surface ofa canal part of the vagina. However, since one of the functions of themuscles surrounding the urethra is to enlarge and contract the urethrawith an appropriate elasticity, even if the conventional elasticitycoefficient or factor for the biological tissue which is represented bythe simple ratio of stress and distortion is used, it is impossible tosufficiently evaluate its elasticity characteristics such asviscoelasticity. Since the diameter of the vagina is in the order of 15mm, it is possible to insert a probe in the canal part thereof. However,in the prior art, there has been no appropriate probe and measuringmethod for measuring the above elasticity of the muscles that surroundthe canal part of the vagina and suspend the urethra. Accordingly, thedetermination of the degree of elasticity deterioration of the musclearound the urethra and the degree of suspending the muscles upwardlyusing the suspension holes for restoring the elasticity is still madethrough a diagnosis relied on experiences such as the palpation of theoperator's fingers.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to overcome theabove problems in the prior art.

It is another object of the present invention to provide an elasticitymeasuring device for biological tissue which is capable ofquantitatively measuring the elasticity of an inner portion of canalpart of the biological body.

According to one aspect of the invention, there is provided anelasticity measuring device for being inserted into a canal part of ahuman body and for measuring elasticity of the inner side of the canalpart of the human body, the device comprising:

-   -   a probe base for being inserted into the canal part of the human        body;    -   a plurality of probes symmetrically arranged around the probe        base, which are located near the inner side of the canal part of        the biological tissue when the device is inserted-into the canal        part and are driven to press onto and return from the biological        tissue;    -   a plurality of resilient arm members each having one end and the        other end, the one end supporting thereon corresponding one of        the plurality of probes and the other end being firmly fixed to        the probe base;    -   a stress detection sensor provided on each of said probes, for        detecting the hysteresis of the stress applied to the biological        tissue based on the repulsion from the biological tissue when        said probes are driven to press onto and return from the        biological tissue; and    -   a deviation detection sensor for detecting the hysteresis of        changes in distance of said stress detection sensor with respect        to the probe base,    -   wherein the elasticity of the biological tissue is measured        based on the hardness and deviation characteristics when the        probes are driven to press onto and return from the biological        tissue;

According to another aspect of the invention, there is also provided anelasticity measuring device for being inserted into a canal part of ahuman body and for measuring elasticity of the inner side of the canalpart of the biological tissue, the device comprising:

-   -   a probe base for being inserted into the canal part of the human        body;    -   a plurality of probes symmetrically arranged around the probe        base, which are located near the inner side of the canal part of        the biological tissue when the device is inserted into the canal        part and are driven to press onto and return from the biological        tissue;    -   a plurality of resilient arm members each having one end and the        other end, the one end supporting thereon corresponding one of        the plurality of probes and the other end being firmly fixed to        the probe base;    -   a hardness sensor provided on each of the probes, for outputting        a signal indicative of hardness of the biological tissue;    -   a hardness detection means for detecting the hardness of the        biological tissue based on the signal from the hardness sensor;        and    -   a deviation detection sensor for detecting the deviation        magnitude of the hardness sensor with respect to the probe base,    -   wherein the elasticity of the biological tissue is measured        based on the hardness and deviation characteristics when the        probes are driven to press onto and return from the biological        tissue.

In the above elasticity measuring device of the invention, it ispreferable that each of the probes comprises a balloon which ishydraulically expandable and contractable and is driven to press ontoand return from the biological tissue.

In the above elasticity measuring device of the invention, the hardnesssensor comprises a vibration element and a vibration detection sensor.The hardness detection means comprises an input terminal connected tothe vibration detection sensor; an output terminal connected to thevibration element; an amplifier having an input coupled to the inputterminal; and a phase shift circuit connected between an output terminalof the amplifier and the output terminal, for changing a frequency andmaking a phase difference zero (0) when there occurs a phase differencebetween input waveforms applied to the vibration element and outputwaveforms forwarded from the vibration detection sensor. With the devicehaving the above structure, while a resonant state of the closed loopcircuit including the hardness sensor and the biological tissue ismaintained, hardness of the biological tissue is preferably detected bythe frequency change caused by the change in hardness of the biologicaltissue.

The elasticity measuring device for the biological tissue of the presentinvention comprises a probe base for being inserted into the canal partof the human body, and a plurality of probes symmetrically arrangedaround the probe base, which are located near the inner side of thecanal part of the biological tissue when the device is inserted into thecanal part and are driven to press onto and return from the biologicaltissue. The contact pressure against the biological tissue, that is, thestress when the probes are driven to press onto and return from thebiological tissue is detected by the stress detection sensor ashysteresis. Also, the deviation magnitude of the stress detection sensorwith respect to the probe base, that is, the deviation magnitude ofexpansion and contraction of the biological tissue is detected by thedeviation detection sensor as hysteresis. Based on these hysteresisdata, the hysteresis of the stress and deviation magnitudecharacteristics of the biological tissue is evaluated and, hence, theelasticity of the biological tissue, for example, the viscoelasticity ismeasured and evaluated experimentally and quantitatively.

The elasticity measuring device for the biological tissue of the presentinvention comprises a probe base for being inserted into the canal partof the human body, and a plurality of probes symmetrically arrangedaround the probe base, which are located near the inner side of thecanal part of the biological tissue when the device is inserted into thecanal part and are driven to press onto and return from the biologicaltissue. The hardness of the biological tissue when the probes are drivento press onto and return from the biological tissue is detected ashysteresis by the hardness detection means based on the signal of thehardness sensor provided on the probe. Also, the deviation magnitude ofthe hardness sensor with respect to the probe base, that is, thedeviation magnitude of expansion and contraction of the biologicaltissue is detected by the deviation detection sensor as hysteresis.Based on these hysteresis data, the hysteresis of the hardness anddeviation magnitude characteristics of the biological tissue can beevaluated. Since the hardness has an intimate or close relationship tothe elasticity coefficient which is a ratio between the stress anddistortion, the elasticity of the biological tissue can bequantitatively measured based on analysis of the hysteresis.

The driving of the probes to press onto and return from the biologicaltissue may well be achieved by the balloon that is hydraulicallyexpanded and contracted, other than the plate spring and motormechanism.

In one embodiment of the elasticity measuring device of the invention,the device comprises a phase shift circuit which functions to change thefrequency and make the phase difference zero (0) when there occurs aphase difference between the input waveforms applied to the vibrationelement and the output waveforms detected by the vibration detectionsensor. With the device having the above construction, while theresonance state of the closed loop circuit including the hardness sensorand the biological tissue is maintained, the hardness of the biologicaltissue can be quantitatively detected based on the frequency changecaused by the change in hardness of the biological tissue, wherebyreliability of quantitative evaluation of hardness hysteresis is highlyenhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will be apparent from the following description of preferredembodiments of the invention explained with reference to theaccompanying drawings, in which:

FIG. 1 is a view showing an embodiment of the elasticity measuringdevice of the invention in the state wherein the device is inserted inthe canal part of the human body;

FIG. 2 is a view for explaining the movement of the probe when the probebase and the sleeve arranged around are moved relatively with each otherin the longitudinal axial direction;

FIG. 3 is a view showing another embodiment of the elasticity measuringdevice of the invention in which balloons are secured to the probe baseas the probes;

FIG. 4 is a view showing the details of the foremost end of the probe ofthe elasticity measuring device of the invention;

FIG. 5 is a graph showing the changes in the stress F (vertical line)and the deviation magnitude X (horizontal line) when the probes of thedevice of the invention are driven to press onto and return from thedesired measuring portion;

FIG. 6 is graphs showing exemplary measured elasticity characteristicswhen the measurements are conducted at different three points of thecanal part of the human body; and

FIG. 7 is a view showing a still further embodiment of the elasticitymeasuring device of the invention using a hardness detection device.

PREFERRED EMBODIMENTS OF THE INVENTION

Now, some preferred embodiments of the present invention are explainedhereunder with reference to the accompanying drawings. FIG. 1 shows astate in which the elasticity measuring device 1 of the invention isinserted in the canal part of the human body 3. The elasticity measuringdevice 1 comprises a probe base 5 in the form of an elongated bar havinga few mm square or a few mm diameter in section, and a probe 7 securedto the probe base 5, a tip portion of which contacts the inner portionof the canal part 3 of the biological tissue and which is driven topress onto and return from the biological tissue to be measured. To theouter surface of the probe base 5, there is provided a sleeve 9 whichhas a slightly larger inner diameter than the dimension of the outwardform of the probe base 5 and which is movable on the probe base 5 in theelongated axial direction of the probe base 5.

The probe 7 includes a plurality of plate springs 15 which aresymmetrically arranged at the outer periphery of the probe base 5, aplurality of stress detection bases 17 correspondingly arranged at theforemost ends of the plate springs 15, and a plurality of contact balls19 made of plastics in the form of substantial hemisphere. The probe 7further includes a stress detection sensor 21 adhered to each stressdetection base 17. A pair of deviation detection sensors 23 are arrangedin such a way that one element is secured to the one side of the platespring 15 whose side is opposite to the side where the stress detectionbase 17 is secured and the other element is secured to a surface of theprobe base 5 which surface is opposing to the side where the one elementis secured. The stress detection sensor 21 and the deviation detectionsensors 23 are connected to a stress calculation device 25 and adeviation calculation device 27, respectively, through correspondingsignal lines. The outputs of both the stress calculation device 25 andthe deviation calculation device 27 are input to an elasticitycalculation device 29. The probes 7 are four (4) in number and arearranged around the probe base 5 in a symmetrical relation. Thesymmetrical relation of the probes 7 is important for the probe base tokeep a stationary state when the measuring device is inserted in thecanal part of the human body.

FIG. 2 is an illustration for explaining the movement of the probe 7when the probe base 5 and the sleeve 9 arranged around the probe base 5are moved relatively with each other in the longitudinal axialdirection. When the sleeve 9 is moved, for example, leftward in FIG. 2with respect to the probe base 5, the tubular inner side of the sleeve 9urges the plate spring 15 of the probe 7, and, in the furtheradvancement of the sleeve 9 in the leftward, it functions to press theplate spring 15 against the probe base side 5. Accordingly, a contactball 19 arranged at the foremost end of the probe 7 moves downward inthe drawings as the sleeve 9 moves in the leftward, whereas it movesupward as the sleeve 9 moves in the rightward. In this way, the contactball 19 at the foremost end of the probe 7 can be driven to press ontoand return from the biological tissue by the simple relative movementbetween the sleeve 9 and the probe base 5. The relative movement betweenthe sleeve 9 and the probe base 5 can be achieved by such small motor asa micro-motor (not shown in the drawings). Further, in the case of asimple measurement, such relative movement between the sleeve 9 and theprobe base 5 can be performed manually by the operator's hands andfingers.

With the leftward movement of the sleeve 9, the probe 7 including thecontact ball 19 can be entirely accommodated within the sleeve 9. Inthis case, since the elasticity measuring device 1 for the biologicaltissue can be inserted to a desired portion of the biological tissue tobe measured in the state in which the probe 7 having the complicatedstructure is fully accommodated within the sleeve 9 being kept, theinsertion of the device can be effected smoothly. Thereafter, at thedesired measuring position after the insertion, the four probes 7 can beopened and closed in an umbrella fashion by the movement of the sleeve9. The number of the probes is not limited to four as in the aboveembodiment, and it may well be any appropriate number, for example, one,two, three, six and so on.

As the structure of the probe which is driven to press onto and returnfrom the biological tissue, other than the above explained plate springstructure, a balloon which is hydraulically expandable and contractablemay well be adopted. FIG. 3 shows such embodiment in which a pluralityof balloons 11 are secured to the probe base 5. The balloon 11 ishydraulically communicated with a pump 13 and is driven to press ontoand return from the biological tissue by the control of the outputpressure of the pump 13.

FIG. 4 shows in detail the foremost portion of the probe 7 shown inFIG. 1. To the foremost end of the plate spring 15, there is adhered thehemispherical contact ball 19 made of plastics having the stressdetection base 17 on the surface thereof opposing to the biologicaltissue. The stress detection sensor 21 is arranged within the stressdetection base 17. The stress detection sensor 21 is a distortion guageand is firmly adhered to the stress detection base 17 using an adhesiveagent. To the side of the plate spring 15 whose side is an opposite sidewhere the reaction detection base 17 is arranged, there is provided alight receiving element. A light emitting element opposing to the lightreceiving element is provided on the surface of the probe base 5. Theabove pair of light emitting and light receiving elements constitutesthe deviation detection sensor 23. The stress detection sensor 21 andthe deviation detection sensor 23 are connected to the stresscalculation device 25 and the deviation calculation device 27,respectively, by the respective signal lines. Though the stressdetection base 17 and the contact ball 19 are made of the same material,they may well be made of different materials and may well be in astacked configuration. The deviation detection sensor, which isconstituted by a pair of the light emitting and light receiving elementin the illustrated embodiment, may well be constituted by a combinationof a magnet and a magnetic sensor, for example, or other smallcontactless sensor.

Next, actual operation of the device having the above structure will beexplained hereunder. The probe base 5 with the four probes 7 arrangedsymmetrically around the probe base 5 being closed in an umbrellafashion is inserted into the canal part of the human body, namely, thevagina of the patient. Then, at the position where the elasticity of thebiological tissue is to be measured, the probes 7 are opened bygradually moving the sleeve 9 relative to the probe base 5 in therightward in FIG. 1. By so doing, the contact ball 19 moves toward thebiological tissue side and urges to press against the biological tissueof the canal part. Thereafter, the sleeve 9 is gradually moved orreturned in the leftward with respect to the probe base 5 so that theprobes 7 are folded. The stress F from the biological tissue at everymoment when the probes drive to press onto and return from thebiological tissue is detected by a pressure detection sensor 21 which isarranged on the stress detection base 17 to which the contact ball 19 isalso provided. In the case where the pressure detection sensor is adistortion guage, the detected result as the variations in resistance isforwarded to the stress calculation device 25 by a signal line andconverted to the corresponding stress after the necessary calculationprocess.

The change in distance of the contact ball 19 with respect to the probebase 5, that is, the relative variation occurring when the contact ball19 is driven to press onto and return from the biological tissue 3 isdetected by the deviation detection sensor 23. Specifically, as thedistance of the contact ball 19 with respect to the probe base 5changes, the distance between the paired light emitting and receivingelements 23 changes accordingly. The change in the amount of receivedlight corresponding to the change in the above distance is forwarded tothe deviation amount calculation device 27 through the signal line andthe magnitude of deviation is obtained thereat after the necessarycalculation process.

In this way, the stress F and the corresponding deviation magnitude Xare obtained under the condition where the probes are driven to pressonto and return from the biological tissue. The probe base 5 ispositioned stationary at the desired measuring point of the biologicaltissue after the insertion and, then, in the case of FIG. 1illustration, the sleeve 9 is gradually moved in the rightward withrespect to the probe base 5 and then gradually moved to the leftwardagain. By so doing, the contact ball 19 is first pressed against thebiological tissue and then returned therefrom. Specifically, by makingthe stress F and the changes in the deviation magnitude X havecorrelation, it is possible to analyze the hysteresis of the elasticityof the biological tissue. FIG. 5 is an exemplary graph which shows thechanges in the stress F and the deviation magnitude X of the biologicaltissue when the probe 7 is driven to press onto and return from thebiological tissue at the desired measuring point. The vertical linedenotes the stress F and the horizontal line denotes the deviationmagnitude X. As shown in FIG. 5, as a hysteresis curve of the elasticityof the biological tissue can be obtained, it has been made possible tomeasure and evaluate the elasticity of the biological tissueexperimentally and quantitatively. The viscoelasticity of the biologicaltissue can be quantitatively evaluated by, for example, the size of areasurrounded by the obtained hysteresis curve.

FIG. 6 shows exemplary graphs of the elasticity when the measurementsare conducted at different three points of the canal part of the humanbody. At the three points A, B and C where the depth of the insertion ofthe probe base 5 into the canal part of the human body are differentfrom one another, the probes 7 are driven to press onto and return fromthe inner side of the canal part of the human body, the hysteresischaracteristics of the stress F and the deviation magnitude X at thattime are obtained and illustrated for the purpose of comparison with thestress F taken as the vertical line and the deviation magnitude X takenas the horizontal line. For example, comparing the hysteresischaracteristics at the point A with those at the point B or C, since thearea surrounded by the hysteresis curve at the point A is smaller thanthe area at the point B or C, it can be quantitatively evaluated thatthe elasticity at the point A is greater than the elasticity at thepoint B or C.

As has been explained hereinabove, it has been made possible to measureand evaluate the elasticity of the biological tissue by evaluating oranalyzing the hysteresis characteristics between the stress and thedistortion based on the measurements of the stress and the distortion ofthe biological tissue. On the other hand, since the hardness has anintimate or close relationship to the elasticity coefficient which is aratio between the stress and the distortion, it is also possible toquantitatively measure and evaluate the elasticity of the biologicaltissue based on the hysteresis of the hardness.

FIG. 7 is a block diagram showing another embodiment of the elasticitymeasuring device for the biological tissue according to the invention,in which the hardness of the biological tissue is measured. A hardnesssensing device 41 includes a vibration element 43 and a vibrationdetector 45 at the foremost end portion of the probe 7. The vibrationelement 43 and the vibration detector 45 are connected to an outputterminal 47 and an input terminal 49, respectively, of a hardnessdetection means 51. The hardness detection means 51 includes anamplifier 53 whose input node is coupled to the input terminal 49, and aphase shift circuit 55 connected between an output node of the amplifier53 and the output terminal 47. The phase shift circuit 55 operates tochange the frequency and make the phase difference zero (0) when thereoccurs a phase difference between the input waveforms applied to thevibration element 43 and the output waveforms forwarded from thevibration detector 45. The detail of such phase shift circuit having theabove functions is disclosed in the Japanese Patent ApplicationKokai-Publication No. Hei 9-145691 which should be incorporated byreference in this application.

In the device having the above construction, while the resonance stateof the closed loop circuit including the hardness sensor 41 and thebiological tissue is maintained, the change in frequency caused by thechange in hardness of the biological tissue is detected by the frequencydeviation detection circuit 57 and, then, the detected change isconverted to the value of hardness by the hardness converter 59. In thisway, with the probe being driven to press onto and return from thebiological tissue, hysteresis characteristics in relation to thehardness of the biological tissue can be quantitatively measured andobtained.

With the elasticity measuring device for the biological tissue accordingto the present invention, the elasticity of the measured biologicaltissue can be quantitatively measured by simply inserting the canal partof the human body with additional simple operation being followed.

While the invention has been described in its preferred embodiments, itis to be understood that the words which have been used are words ofdescription rather than limitation and that changes within the purviewof the appended claims may be made without departing from the true scopeof the invention as defined by the claims.

1. An elasticity measuring device for being inserted into a canal partof a human body and for measuring elasticity of the inner side of thecanal part of the human body, said device comprising: a probe base forbeing inserted into the canal part of the human body; at least one probearranged around said probe base, which is located near the inner side ofthe canal part of the human body when the device is inserted into thecanal part and is driven to press onto and return from the biologicaltissue; a resilient arm member having one end and the other end, saidone end supporting said at least one probe thereon and said the otherend being firmly fixed to said probe base; a stress detection sensorprovided on said probe, for detecting hysteresis of the stress appliedto the biological tissue based on the repulsion from the biologicaltissue when said probe is driven to press onto and return from thebiological tissue; and a deviation detection sensor for detecting thehysteresis of changes in distance of said stress detection sensor withrespect to said probe base, wherein the elasticity of the biologicaltissue is measured based on the stress and deviation magnitudecharacteristics when the probe is driven to press onto and return fromthe biological tissue.
 2. An elasticity measuring device for biologicaltissue according to claim 1, in which said resilient arm membercomprises a plurality of spring members, a plurality of said probesbeing symmetrically arranged around said probe base throughcorresponding spring members.
 3. An elasticity measuring device forbiological tissue according to claim 2, in which said deviationdetection sensor comprises a pair of light emitting element and lightreceiving element, said light emitting element being secured on asurface of said probe base and said light receiving element beingsecured on said spring member so as to oppose to each other.
 4. Anelasticity measuring device for biological tissue according to claim 1,in which said stress detection sensor comprises a distortion guage. 5.An elasticity measuring device for being inserted into a canal part of ahuman body and for measuring elasticity of the inner side of the canalpart of the human body, said device comprising: a probe base for beinginserted into the canal part of the human body; at least one probearranged around said probe base, which is located near the inner side ofthe canal part of the biological tissue when the device is inserted intothe canal part and is driven to press onto and return from thebiological tissue; a resilient arm member having one end and the otherend, said one end supporting said at least one probe thereon and saidthe other end being firmly fixed to said probe base; a hardness sensorprovided on said probe, for outputting a signal indicative of hardnessof the biological tissue; a hardness detection means for detecting thehardness of the biological tissue based on the signal from said hardnesssensor; and a deviation detection sensor for detecting the deviationmagnitude of said hardness sensor with respect to said probe base,wherein the elasticity of the biological tissue is measured based on thehardness and deviation characteristics when the probe is driven to pressonto and return from the biological tissue.
 6. An elasticity measuringdevice for biological tissue according to claim 5, wherein said hardnesssensor comprises: a vibration element; and a vibration detector, andwherein said hardness detection means comprises: an input terminalconnected to said vibration detector; an output terminal connected tosaid vibration element; an amplifier having an input coupled to saidinput terminal; and a phase shift circuit connected between an outputterminal of said amplifier and said output terminal, for changing afrequency and making a phase difference zero (0) when there occurs aphase difference between input waveforms applied to said vibrationelement and output waveforms forwarded from said vibration detector,wherein, while a resonant state of the closed loop circuit includingsaid hardness sensor and the biological tissue is maintained, hardnessof the biological tissue is detected by said frequency change caused bythe change in hardness of the biological tissue.
 7. An elasticitymeasuring device for biological tissue according to claim 1 or 5, inwhich said probe comprises a balloon which is hydraulically expandableand contractable and is driven to press onto and return from thebiological tissue.